What is the Difference between Psychosis and Nervous Breakdown? Terms «psychosis» and «nervous breakdown / affective reaction» are often confused. We often hear: «I’ve gone crazy», which means that a man could not restrain himself. In fact, this is a sudden outburst of anger, hysteria, which is characteristic of mentally healthy person. These problems can be corrected both by person himself and by psychologist. Psychosis is a more complex and difficult condition treated by psychiatrist. It is understood as mental disorder, expressed violation of mental activity, disturbance of perception of real world (attention, memory, thinking) and disorganization of behavior.